The increasing market of wireless personal area networks (WPAN) and wireless body area networks (WBAN) demands ultra low power low cost wireless transceivers. Although many different wireless transceivers have been developed, there are some common features required by these transceivers in physical layer, such as the amplitude shift keying (ASK), frequency shift keying (FSK), Gaussian frequency shift keying (GFSK) modulators and demodulators (modems).
In order to handle these common modulation schemes, the conventional wireless transceivers implement individual modems for each modulation scheme, and simply physically put them into one chip. The modulation schemes for the conventional wireless transceivers are hard switched, are not flexible and reconfigurable. Therefore, there is unavoidable waiting time for switching the modulation schemes. For example, some conventional data link modules, which have both the ASK demodulator and the FSK demodulator, use one control bit to power ON/OFF one of the demodulators to switch the required scheme. Hence, there is a waiting time for switching to the desired modulation scheme and initializing the demodulator.
Further, since the conventional transceivers simply hard switch individual modems, the design is not optimized as one reconfigurable multi-scheme modem, the chip area is large, and thus the cost is high.
Further, the individual modulators and demodulators in the conventional transceivers also consume high power and high cost. For example, for the widely used FSK and/or GFSK schemes, phase locked loop (PLL) based demodulator, digital based demodulator, delay line or delay locked loop (DLL) based demodulator, and I/Q frequency discriminator based demodulator are generally used. However, these demodulators consume high power and take up a large chip area. Therefore, these demodulators are not suitable for the new generation WPAN and WBAN applications.
Further, the conventional transceivers which use FSK and/or GFSK modulation scheme normally have only one channel communication. They do not perform multi-channel communication like the QAM modulation scheme. The channel efficiency and spectrum efficiency are not high.
Therefore, it is desirable to provide a modulator, a demodulator and a modulator-demodulator which can achieve zero delay time modulation scheme switching, multi-scheme reconfigurable modulation demodulation data link, low power consumption, small chip area, high phase accuracy, and dual-channel high channel efficiency complementary amplitude and frequency shift keying (CAFSK) communication.